Compact power transfer mechanism using induced emf

ABSTRACT

What is presented is a power-transfer system that provides resonant inductive power from a first object to a second object, which is adjacent to the first object. The system includes a first transformer portion that is positioned on the first object and having a first core portion. The first core portion includes a transmit unit configured to transfer an electromagnetic field to the second transformer portion. The first core portion also includes first circuitry that allows the transmit unit to transfer the electromagnetic field. The second transformer portion is positioned on the second object and has a second core portion. The second core portion includes a receiver unit configured to receive the electromagnetic field. The second core portion also includes second circuitry that allows the transmit unit to transfer the electromagnetic field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent Application Ser. No.62/147,397, filed Apr. 14, 2015, the contents of which are herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to power-transfer devices and systems forproviding a resonant inductive power coupling between a first object anda second object; more particularly, to such a device or system whereinsaid first and second objects are not physically connected electrically;and most particularly, to providing electric power to a lock mechanismfor electrically locking or unlocking a door mounted in a frame via atransformer arrangement having a transmitter portion and a receiverportion. The transformer arrangement may reside in a mortise-type lockset having a latch electrically retained or released from its relatedstrike or the transformer arrangement may reside in the edge of the doorand adjacent surface of the door frame separate from a lock set.

BACKGROUND OF THE INVENTION

The need to transfer power through air or othernon-magnetic/non-conducting materials is becoming vital throughouttoday's world. One way to accomplish this need is through theimplementation of inductive or resonant inductive power couplingdevices. Such devices can be used to recharge the batteries ofelectronic devices and electric automobile batteries as well as couplingstationary equipment to rotating armatures or powering hypo-dermalmedical devices. Particularly, in the access control field, there hasbeen a long-felt need to power electrified locking mechanisms, residingin a door, by a method that does not require running any type of wiringthrough the environment in which the locking mechanism is installed(e.g. running wires through the hinges connecting a door to acorresponding door frame) as well as does not require cross drillingthrough the door or using spring loaded power contacts, which becomeexposed when the door is in the open position. Resonant inductivecoupling having one portion mounted in the door and a correspondingmating portion mounted in the door frame provides a viable solution tothe industry's long-felt need but also poses challenges for those withskill in the art, such as ensuring the electromagnetic field properlytransfers across the distance of the gap between the door and itscorresponding door frame (or, in certain instances, a mullion),regardless of the gap's unique characteristics, and the need for theinstalled components to occupy a minimal amount of space such as no morethan a one inch diameter space in the door and a one inch diameter spacein the door frame. Another challenge posed to the skilled artisan,particularly when using solenoid actuators, is that no less than sixwatts of power must be transferred from the door frame to the door for aduration of time that is long enough to move the actuator (load), whichin turn ultimately releases the locking mechanism.

Prior art systems transfer power and/or data between a door and a doorframe with wires that run through a mechanical hinge point or a set ofspring loaded contacts that provide an electrical connection across thedistance of the gap between the door and corresponding door frame, whenthe door is in the closed position. The problem with this wire-basedapproach is that only fine wires with very small diameters can be used,since such wires must pass internally through the plates of the doorhinges to avoid being severed during normal operation or by an unwantedintruder. The spring-loaded contacts approach presents a different setof problems relating to contamination of the contacts and the risk ofelectrical shock if the user comes into physical contact with theelectrically active contact portion installed on the frame.

Alternative prior art systems have achieved both power and datatransmissions between a door and a door frame. For instance, U.S. Pat.No. 8,294,302 and U.S. Pat. No. 9,290,966, both assigned to HanchettEntry Systems, Inc. with the relevant disclosure of each incorporatedherein by reference, disclose devices that avoid system limitations dueto intervening and variable gaps between the door and frame by provisionof spring loaded members, which place the opposing transmitter/receiverunits within close proximity with one another to thereby enableefficient power transfer. However, these systems require at least thetransmitter component or the receiver component to extend outwardly andbeyond the plane of the door or door frame where it will be exposed andprone to damage or become disabled.

What is needed in the art is a robust and efficient system that provideswire-free power transfer between a door frame and a door, while avoidingthe limitations in the prior art, discussed above.

What is further needed in the art is a compact system that will occupy aminimal amount of area in a door edge or door frame.

What is yet further needed in the art is a system wherein its circuitryoptimizes the power output of the device.

It is a principal object of the present invention to provide a compact,wire-free power transmission system wherein the transmitter and receiverare seated flush within their respective door or door frame whilesimultaneously compensating for the distance of the gap between the doorand corresponding door frame, regardless of the gap's uniquecharacteristics (i.e. gap distance,)

SUMMARY OF THE INVENTION

What is presented is a power-transfer system that provides resonantinductive power from a first object to a second object, which isadjacent to the first object. The system includes a first transformerportion that is positioned on the first object and having a first coreportion. The first core portion includes a transmit unit configured totransfer an electromagnetic field to the second transformer portion. Thefirst core portion also includes first circuitry that allows thetransmit unit to transfer the electromagnetic field. The secondtransformer portion is positioned on the second object and has a secondcore portion. The second core portion includes a receiver unitconfigured to receive the electromagnetic field. The second core portionalso includes second circuitry that receives the electromagnetic fieldand converts it to DC voltage.

In certain embodiments of the system, the system comprises atimer/sensor, located in the first transformer portion that isconfigured to monitor the position of the second object. Moreover, thetimer/sensor can be embodied as a reed switch that is influenced by apermanent magnet positioned on the second object. In certain instances,a timing circuit can be incorporated into the timer/sensor. This timingcircuit is to limit the duration of time that power can be provided to aload. In certain instances, an auxiliary position sensor is used inconjunction with the timer/sensor. This auxiliary position sensor isconfigured to sense the specific position of the second object incomparison to the first object.

In certain embodiments of the system, the first circuitry comprises avoltage regulator, Royer oscillator, and rectifier. The voltageregulator is configured to control the voltage from a power sourceproviding a fixed output independent of the input voltage over a certainrange. The Royer oscillator is configured to transform the DC voltageoutput from the voltage regulator into two positive going half sine wavesignals which are applied to two opposite terminals of an LC tankcircuit. The rectifier converts the two sine wave signals back to a DCvoltage which is sent to the feedback pin of the voltage regulator tocontrol the voltage output from said Royer oscillator.

In certain embodiments of the system, the second circuitry comprises arectifier and voltage regulator. The rectifier is configured to convertthe AC voltage induced in the receiver unit back to DC voltage. Thevoltage regulator is configured to maintain a constant voltage level ofthe output from said rectifier. In certain instances, the secondcircuitry also comprises an output voltage selector that is configuredto allow the voltage supplied to the load to be selected by a user.

Although not a requirement, the first object can be a door frame and thesecond object can be a door that is movably connected to the door frame.An open circuit can be created when said transmit unit is beyond theproximity limit of said receiver unit. The first transformer portion andsecond transformer portions can each have an external diameter of oneinch or less.

Numerous applications, some of which are exemplarily described below,may be implemented using the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 a perspective view of the environment that an embodiment of thepower transfer system is installed, in accordance with the presentinvention;

FIG. 2 is an exploded view of a strike plate and first transformerportion of the embodiment of FIG. 1;

FIG. 3 is an exploded view of the lock body and second transformerportion of the embodiment of FIG. 1; and

FIG. 4 is a block diagram of an embodiment of the power transfer system.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate currently preferred embodiments of the present invention, andsuch exemplifications are not to be construed as limiting the scope ofthe invention in any manner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 through 4, an embodiment of a resonant inductivepower coupling transfer system (hereinafter “power-transfer system”) isgenerally indicated by reference numeral 10. Power-transfer system 10includes a first transformer portion 34 (FIG. 2) and a secondtransformer portion 32 (FIG. 3). In this embodiment, the power-transfersystem 10 is substantially contained in a mortise lock set having a doorunit 12 and a frame unit 14. However, it is under stood thatpower-transfer system 10 need not be contained within a lock set.

Door unit 12 generally includes a first object that is a lock body 16 inthis embodiment. The lock body 16 is inserted within a mortise cut 18into the edge 20 of a door 22, proportioned so as to create a frictionfit between the lock body 16 and door 22. A face plate 24 covers anygaps between the lock body 16 and the face of edge 20 as well asprotects the internal mechanisms housed within the lock body 16. Faceplate 24 is generally adapted to fit flush with the edge surface of thedoor 22, when properly secured. Lock body 16 is equipped with a latch26, which passes through latch aperture 28 on a second object that is astrike plate 30 in this embodiment. The strike plate 30 engages within arecess (not shown) in the door frame so as to secure the door in aclosed position. Latch 26 may be an electrified latch powered bypower-transfer system 10.

The embodiment of the power-transfer system 10 shown in FIG. 1 residesin an area typically occupied by a dead bolt mechanism. An inductivelycoupled power-transfer unit (second transformer portion 32) replaces thedead bolt slide in the door. Similarly, a corresponding inductivelycoupled power-transfer unit (first transformer portion 34) is situatedproximate the opening typically reserved in strike face plate 14 forpassage of the deadbolt slide when the deadbolt is engaged. The firsttransformer portion 34 is configured to operate as a transmitter whilethe second transformer portion 32 is configured to operate as thecorresponding receiver. As follows, it is envisioned that properlymounted mortise locks (currently mounted within structures such as, butnot limited to, homes and businesses) may be retrofitted with thepresent embodiment of the power-transfer system 10, as shown in FIG. 1,with no or minimal need of any additional physical modifications to thedoor, frame, or other corresponding components. Alternatively, door 22and the door frame may be adapted to include opposing recessesrespective to the first transformer portion 34 and second transformerportion 32. In one aspect of this embodiment, the door and door framerecesses have diameters less than or equal to one inch to accommodatethe first and second transformer portions.

Referring now to FIG. 2, frame unit 14 includes strike plate 30 forreceiving first transformer portion 34. Strike plate 30 includesapertures 28 and 36 formed therein. Aperture 28 is sized to acceptinsertion of a latch 26 (see FIGS. 1 and 3) when strike plate 30 isproperly positioned and secured on a door frame. In this embodiment,aperture 36 is configured to receive first transformer portion 34, whichis generally comprised of a cap member 38 and a housing member 40.Housing member 40 may be generally cylindrical. Positioned withinhousing member 40 is a first core portion 42, discussed in more detailbelow with regard to FIG. 4.

Cap member 38 includes a top-cover portion 44, which is proportioned tobe slightly larger than the diameter of aperture 36 such that cap member38 rests against the door-facing surface of strike plate 30 whenproperly mounted. Alternatively, it should be understood that strikeplate 30 may include a stepped portion (not shown) configured to receivetop-cover portion 44 such that the top-cover portion 44 sits flush withthe door-facing surface of the strike plate 30. Cap member 38 furtherincludes a sidewall having a first sidewall portion 46 and a secondsidewall portion 48, each configured to extend through strike plate 30and into a recess formed in the door frame (not shown). In thisembodiment, as stated above, the recess formed in the door frame has amaximum diameter of one inch (1″). First sidewall portion 46 isproportioned to be equal to or slightly larger than the diameter of thedoor frame recess. In this manner, the first sidewall portion 46 willengage the door frame through a friction fit. First sidewall portion 46may also include ramp features and/or fin features that increasefrictional forces between cap member 38 and the frame recess, as well asreduce the possibility of unwanted withdrawal of first transformerportion 34 from the door frame and strike plate 30. Second sidewallportion 48 is proportioned to frictionally receive housing member 40 ashousing member 40 slides over second sidewall portion 48. While theabove fastening means have been described as friction fits, alternativefasteners may be used, such as threaded connections between strike plate30 and first sidewall portion 46 or between second sidewall portion 48and housing member 40, or by using additional threaded fasteners suchas, but not limited to, screws, bolts, or set screws, or by using asuitable adhesive.

FIG. 3 provides an exploded view of second transformer portion 32 ofpower-transfer system 10 in relation to door unit 12. Similar to thefirst transformer portion 34, discussed above, second transformerportion 32 generally includes a cap member 38 and a housing member 40.Housing member 40 may be generally cylindrical. Positioned withinhousing member 40 of second transformer portion 32 is a second coreportion 52. Second transformer portion 32 is configured to reside withina recess (not shown) in lock body 16 by passing through aperture 50,defined within face plate 24. Top cover portion 44 rests along thestrike plate-facing surface of face plate 24, and may reside within astepped groove so as to sit flush with the face plate. First sidewall 46engages the recess and/or side surface of aperture 50 so as to securesecond transformer portion 32 within lock body 16. As described above,second sidewall portion 48 is proportioned to receive housing member 40as housing member 40 slides over second sidewall portion 48 and isconnected to the second sidewall portion 48 through friction fitting.While the above fastening means have been described as friction fitting,alternative fasteners may be used, such as threaded connections betweenlock body recess and/or face plate 24 and first sidewall portion 46 orbetween second sidewall portion 48 and housing member 40, or by usingadditional threaded fasteners, such as, but not limited to, screws,bolts, or set screws, or by using a suitable adhesive.

With reference to both FIGS. 2 and 3, each of the core portions 42 and52 may generally be comprised of a core half, such as, but not limitedto, pot core halves 60 (FIG. 2) and 70 (FIG. 3), respectively, having acylindrical post 72 and a magnetic bobbin (64 and 74, respectively)wound with electrically conductive coils. Electrical current is suppliedto the set of coils wrapped around bobbin 64 to generate an alternatingcurrent (AC) electromagnetic field. The electromagnetic field emanatesdirectly from the coils on bobbin 64, causing the coils to functiontogether as a transformer. In this embodiment, the coils have anapproximately 0.75 inch diameter. The components of the core portions 42and 52 are installed onto printed circuit boards (PCBs) 43 and 53,respectively, or the equivalent, having an approximately 0.90 inch widthand an approximately 1.5 inch length, to allow for easy installationinto the respective housing member 40. If, and when, second core portion52 is properly within the electromagnetic field generated by the firstcore portion 42, an induced AC current is generated by the coils woundaround bobbin 74, discussed below. This induced electrical current maythen be transferred to any desired load, which is typically anelectronic device, such as, but not limited to, an electric lock orelectric key pad.

In accordance with an aspect of the present invention, the packagedensity for the transformer portions 32, 34 (and associated coreportions 42,52) is required to comply with the established NFPA standardto allow for the door to be endorsed with a fire label. In thisembodiment, the housing member 40 for each core portion 42 and 52 has anexternal diameter of one inch (1″) or less, as current fire codes forfire door applications restrict any recesses formed in the door to beone inch or less. A pot core such as Part #22-13-00, available from TSCFerrite International, Wadsworth, Ill., meets the necessaryspecifications to support the configuration of this embodiment of thepresent invention. However, one having ordinary skill in the art willsee that other equivalent pot cores or air coils and components may meetthe necessary specifications of this embodiment.

As described above with regard to FIG. 1, each of the core portions 42and 52 are fixedly mounted to a respective door frame or door, with theintervening gap between the core portions 42 and 52. In essence, whenthe first core portion 42 is mounted to the door frame, thecorresponding second core portion 52 is mounted to the correspondingdoor. The gap between the core portions 42 and 52 may align with thedistance between the edge of the door and corresponding door frame. Itshould be understood that while the gap is fixed and defined by thedistance between a particular door and its particular frame, the gapdistance is unique to each installation and may vary from one door/doorframe unit to the next. It should also be understood that thisembodiment is not necessarily required to be installed within a door anddoor frame of a traditional structure. One having ordinary skill willsee that this embodiment of the power-transfer system 10 may also beinstalled in other environments such as, but not limited to, the doorand door frame of an automobile or a secured lock box as well as thematching gate doors of a gate entryway.

With reference to FIG. 4, in this embodiment, core portions 42 and 52include respective circuitry 76 and 78 designed to compensate for uniquecharacteristics of the distance of the gap between a particular door andits particular door frame. For instance, core portions 42 and 52 canproperly transfer an electromagnetic field across the distance of a gapwhen it is several millimeters in length. The core portions 42 and 52can also properly transfer the electromagnetic field throughnon-magnetic/non-conductive materials situated directly between therespective door and door frame.

The first core portion 42 comprises first circuitry that is configuredto allow it to operate as a transmitter of the electromagnetic field.The first core portion 42 may include a voltage regulator 80 to receiveDC voltage from a power supply 82. The voltage regulator 80 controlsthis DC voltage at its output and causes the voltage to become constant.The constant voltage is then provided to a Royer oscillator 84, whichthen transforms this constant voltage from DC to AC at the output. Incertain instances, the Royer oscillator 84 will convert the constantvoltage to an AC voltage having a sinusoidal waveform. A rectifier 86 isconnected to the output of the Royer oscillator 82 and conditions theoutput to a lightly-filtered DC voltage. Positioning a rectifier 86within the first circuitry at this location allows the output voltagefrom the Royer oscillator 84 to become fixed in spite of the variableinductance that is seen across the Royer oscillator 84 as the first coreunit and second core unit are moved apart. The DC voltage conditioned bythe rectifier 86 is then applied to the feedback input 80 a of thevoltage regulator 80. Voltage regulator 80 may further operate using asingle-ended primary-inductor converter (SEP IC) topology, to vary thevoltage at the output of the voltage regulator 80 (i.e. to control theoutput voltage of the voltage regulator 80). The output voltage of thevoltage regulator is typically set to be the value required for thesecond core output voltage of 12 volts pick and 6 volts hold. “Pick”voltage is the voltage needed to draw an armature toward an associatedelectromagnet/solenoid and “hold” voltage is the voltage needed to holdthe armature within the magnetic field of the associatedelectromagnet/solenoid.

In this manner, the AC voltage outputted from Royer oscillator 84remains constant as it is applied to the transmit unit 65 containingfirst core portion 42, which is typically a tightly wound coil wrappedaround the bobbin 64 of first core portion 42. The equation representingthe inductance as seen at the input of transmit unit 65 is as follows:

L_(transmit effect) K√{square root over (L_(transmit)×L_(receive))}

Where L_(transmit effect) is the effective inductance and the constant Krepresents the coupling of the two coils as determined by the gapdistance between the transmit unit 65 and a receiver unit 75 containingsecond core portion 52, which is typically a tightly wound coil wrappedabout the bobbin 74 of second core portion 52.

By maintaining a constant voltage into the transmit unit 65, a constantand oscillating electromagnetic field is in turn generated by thehighly-resonant transmit unit 65. This electromagnetic field is thentransmitted from the transmit unit 65 beyond the distance of the gap,where it is subsequently received by the receiver unit 75. The receiverunit 75 is able to substantially receive at least a portion, andpreferably substantially all, of the electromagnetic field beingtransmitted over the gap, regardless of the distance. The constantelectromagnetic field then induces a constant AC current in the receiverunit 75, as described above. This communication completes the near-fieldwireless transmission of the electromagnetic field between the transmitunit 65 and receiver unit 75. The current induced in the receiver unit75 also typically oscillates at the same general frequency as thecurrent of the electromagnetic field transferred across the gap by thetransmit unit 65. With the transmit unit 65 and receiver unit 75resonating at a common frequency, significant power may be transmittedbetween these coils with reasonable efficiency. This in effect alsoensures that the receiver unit 75 optimally absorbs the energy from theelectromagnetic field. The transmit unit 65 and receiver unit 75 mayalso each be a single layer coil. It should be understood thatcomponents can be modified in the second circuitry to off-tune thesecondary circuit with respect to the frequency of the electromagneticfield generated from the transmit unit 65. This technique enables afairly constant voltage out of the second circuitry in spite of theseparation variability between the door and the jamb.

The second core portion 52 comprises second circuitry that is configuredto allow it to operate as a receiver. After the electromagnetic field isreceived by the receiver unit 75, the induced current may then berectified by a rectifier 90 that is directly in series with the receiverunit 75, to convert the AC voltage back to DC voltage. A voltageregulator 92 may then be positioned in series with the rectifier 90, tomaintain a constant output voltage level. This regulated DC voltage maythen power a load 94 (located outside of the circuit), which may be anelectromagnetic actuator within door unit 12. In certain instances, anoutput voltage selector 96 is included within second core portion 52.The output voltage selector 96 causes the voltage supplied to the load(e.g., 12 V DC or 24 V DC) to be selected by a user, either in theenvironment in which the power-transfer system 10 is installed orremotely through some means of communication (e.g. via the internet),depending upon the particular system requirements.

When the door is in the closed position within the door frame, such thatthe transmit unit 65 is in proximity with the receiver unit 75 and theelectromagnetic field can be properly transferred to the receiver unit75, the electric circuit of the power-transfer system 10 is complete.Thus, when a single pulse of power is emitted from an access controlprocessor 100 (such as through a key pad, card reader, fob reader, orthe like) to power supply 82, the power supply 82 is activated toprovide the actuator (load 94) with maximum power for a short fixedinterval via the induced current received by the receiver unit 75, so asto unlock the latch and enable its withdrawal from an aperture in thestrike plate. This, in effect, ultimately allows the door to be opened.During pick time (the duration of time that full power is applied to theload 94) both voltage out and current out levels are increased throughthe voltage regulator 80. During hold time (the duration of time thatthe power to load 94 has been stepped down so as to hold the latch inthe powered state), both output voltage and current are limited toprotect Royer oscillator 84 from overheating, thus, reducing the risk ofuser exposure to unsafe temperatures and protecting the electroniccomponents and associated circuitry on both frame and door sides. Itshould be noted when the transmit unit 65 is not in proximity with thereceiver unit 75 (i.e. typically when the door is in the open position),an open circuit is created and voltage is lost in the second transformerportion 32. When this occurs, power cannot transfer from the transmitunit 65 to the receiver unit 75. Thus, activating the power supply 82would not provide power to the load 94. The open circuit is typicallycreated when the distance between the transfer unit and the receiverunit 75 is over 0.5 inches.

In certain instances, a sensor unit 88 a may be implemented to monitorthe door position. For example, the sensor unit 88 a may be a reedswitch that is influenced by the magnetic field created by a permanentmagnet 98 installed on the second core portion 52 that is positioned onthe door 22. When the magnetic field created by the permanent magnet isout of the range of the sensor unit 88 a, the sensor unit 88 maintainsthat the power supply remains off and without power. Thus, by using thesystem of a reed switch and associated permanent magnet, the transmitterremains unpowered while the door is in the open position. In certaininstances, an auxiliary position sensor 88 b may also be employed toensure proper monitoring of the door position. It should be understoodthat, functionally, the sensor unit 88 a as well as the auxiliaryposition sensor 88 b may incorporate any suitable sensor system capableof sensing when the door is closed and not closed, such as, but notlimited to, a photo sensor, a pressure sensor, a micro switch, a passiveinfrared sensor, a radio frequency (RF) sensor, a second reed switch, orthe like. A timing circuit 89 may also be implemented. The timingcircuit may be employed to limit the duration of time that power can beprovided to the load 94. For instance, the timing circuit may beinitiated by either the powering up of power supply 82 or by the doorreturning to the closed position, as discussed above with regard toFIG. 1. It should be understood that the timing circuit 89 mayincorporate any suitable timing system capable of limiting the durationof time that full power can be provided to the load 94 (such as, but notlimited to, a 555 timer IC chip).

It should be understood that the power transfer system 10 is notnecessarily required to be installed in a door and corresponding doorframe or mullion discussed in detail for the above disclosed embodiment.In certain applications, an embodiment of the power-transfer system 10may be used to charge the batteries of portable devices (such as, butnot limited to, cellular phones and tablet computers) at a distance andwithout the portable device being tethered to a power outlet. In otherapplications, an embodiment of the power-transfer system 10 may be usedto provide electric power in medical implantable devices and/orhypo-dermal medical devices. In other instances, an embodiment of thepower-transfer system 10 may be used to provide an electrical connectionthrough the rotating joints of the armatures of mounted medical armdevices, robotics, and the like. In other instances, an embodiment ofthe power-transfer system 10 may be used for recharging electricautomobiles that are parked in certain parking spots and parking garagesthat are equipped with a core portion having a transmit unit. In each ofthese a skilled artisan will see how each application of thepower-transfer system 10 can be properly installed into its respectiveenvironment to sufficiently meet the needs of the power-transfersystem's 10 application.

While the invention has been described with reference to preferredembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements or components thereof to adapt to particular situations withoutdeparting from the scope of the invention. Therefore, it is intendedthat the invention not be limited to the particular embodimentsdisclosed as the best mode contemplated for carrying out this invention,but that the invention will include all embodiments falling within thescope and spirit of the following claims.

What is claimed is:
 1. A power-transfer system for providing resonantinductive power from a first object to a second object, wherein thefirst object and the second object are adjacent with respect to eachother, said system comprising: a) a first transformer portion positionedon the first object and having a first core portion, said first coreportion comprising: i) a transmit unit configured to transfer a constantAC electromagnetic field from said first transformer portion to saidsecond transformer portion; and ii) first circuitry configured to allowsaid transmit unit to sufficiently transfer the electromagnetic field;b) said second transformer portion positioned on the second object andhaving a second core portion, said second core portion comprising: i) areceiver unit configured to receive the electromagnetic field; and ii)second circuitry configured to allow said transmit unit to sufficientlytransfer the electromagnetic field.
 2. A system in accordance with claim1 further comprising a sensor configured to monitor the position of thesecond object.
 3. A system in accordance with claim 2 further comprisinga timing circuit configured for limiting the duration of time that fullpower can be provided to a load.
 4. A system in accordance with claim 1further comprising: a sensor configured to monitor the position of thesecond object; and an auxiliary position sensor configured to sense thespecific position of the second object in comparison to the firstobject.
 5. A system in accordance with claim 2 wherein said sensor is areed switch influenced by a permanent magnet positioned on the secondobject.
 6. A system in accordance with claim 1 wherein said firstcircuitry comprises: a) a voltage regulator configured to control thevoltage from a power source; b) a Royer oscillator configured totransform the voltage output from said voltage regulator; and c) arectifier connected to the outputs of said Royer oscillator andconfigured to condition the voltage output from said Royer oscillator,wherein the rectified Royer oscillator output signals are used tocontrol output voltage of the voltage regulator.
 7. A system inaccordance with claim 1 wherein said first circuitry comprises: a) avoltage regulator configured to stabilize the voltage from a powersource; b) a Royer oscillator configured to transform the voltage outputfrom said voltage regulator; and c) a rectifier connected to the outputsof said Royer oscillator and configured to condition the voltage outputfrom said Royer oscillator.
 8. A system in accordance with claim 7wherein said voltage regulator is configured to operate using SEP ICtopology.
 9. A system in accordance with claim 1 wherein said secondcircuitry comprises: a) a rectifier configured to convert the AC voltageinduced in said receiver unit to DC voltage; and b) a voltage regulatorconfigured to maintain a constant voltage level of the output from saidrectifier.
 10. A system in accordance with claim 9 wherein said secondcircuitry further comprises an output voltage selector configured toallow the voltage supplied to a load to be selected by a user.
 11. Asystem in accordance with claim 1 wherein the first object is a doorframe and the second object is a door movably connected to the firstobject.
 12. A system in accordance with claim 1 wherein an open circuitis created when said transmit unit is beyond the proximity of saidreceiver unit.
 13. A system in accordance with claim 1 wherein theresonant frequency of the second circuitry is off-tuned from the generalfrequency of the electromagnetic field generated by the first circuitry.14. A system in accordance with claim 1 wherein one of said first orsecond transformer portion is cylindrically shaped.
 15. A system inaccordance with claim 13 wherein said first or second transformerportion is no more than one inch in diameter.